On Wed, Jun 15, 2016 at 9:14 AM, Jan Beulich <jbeul...@suse.com> wrote:
> >>> On 15.06.16 at 12:45, <andrey2...@gmail.com> wrote: > > In reply to - > > http://lists.xen.org/archives/html/xen-devel/2016-06/msg00622.html > > > > HI, I am working with Jurgen on the issue, as per Jan's request I tried > to > > write explicitly only latency timer to be written - > > bool force_write = false; > > if ((dev_data->permissive || xen_pcibk_permissive) && > > offset == PCI_CACHE_LINE_SIZE && size == 4) > > force_write = true; > > ... > > > > if ((force_write || !handled) && !err) {...} > > > > But then it exposed another issue, the command register field seems not > to > > be restored also > > because I think the bits which are to be restored are not > > in PCI_COMMAND_GUEST mask. > > Please be more precise: Which bits in particular are not getting > set back to the needed values (I would guess the memory > and/or I/O decode ones, which we specifically must not allow > the guest to control, but I'd like to be certain)? > Indeed, 0x103 which would be MEMORY,IO and SERR. > > If my guess is correct, then I think rather than adding some > hackish workaround to pciback you'd better see whether there's > a way to cause a pci_disable_device() through your driver before > the reset, and a pci_enable_device() after. Or actually, I think > you can do this via plain config space writes from your driver: Try > writing the Command Register with the two decode bits clear > right before restoring the intended value (see the logic close to > the top of command_write()). > > Jan > > So i tried the first option, as you suggested by writing to /sys/bus/pci/devices/0000\:00\:00.0/enable '0' == disable before reset and '1' == enable after from the test app, but no writes get through to pic-back on DOM0 , only the reads. But this basically still tries to write the MEMORY and IO bits to command register down the call stack in pci_enable_resources <http://lxr.free-electrons.com/ident?i=pci_enable_resources> which would again be blocked in xen-pciback xen_pcibk_config_write or am I missing something ?
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